Product Overview

BAC-1xx63/1xxx63 Series (6 Relays and 3 Analog Outputs) Section 49 Application Guide S
tration at the end of the last fan operation period to CO2 Max and the
allowed ventilation rate for this fan cycle. Should there be a continued
call for heating or cooling after the recovery period is complete, Ventila-
tion mode shall return to NORMAL.
Whenever the supply fan stops, Space CO2
is recorded (Space CO2
Last) at the time the fan stops. A timer, Fan O Timer, keeps track of the
elapsed time in minutes the supply fan was o during the occupied pe-
riod since the end of the last fan operation or the end of the last Standby
period.
Whenever the supply fan starts after an o period, except in Standby
mode, the ventilation shall be maintained at the following position, OA
Recov Pos:
1. If OA is above Clg Design Temp (95° F default) or below Htg Design
Temp (20° F default), the OA damper shall be set to OA Full.
2. If OA is between OA Low Vent (65° F default) and OA High Vent
(80° F default), the OA damper shall be set to 100% open.
3. If OA is between Htg Design Temp (20° F default) and OA Low Vent,
the OA damper shall be proportionally set between OA Full and
100%.
4. If OA is between OA High Vent and Clg Design Temp (95° F default),
the OA damper shall be proportionally set between 100% and OA
Full.
5. OA Max does not apply during RECOVERY mode.
In order to nd the ventilation recovery time (Fan Recov Timer), the fan
recovery ratio (Fan Recov Ratio) must be calculated. Fan Recov Ratio is
the prescriptive ventilation needed as a fraction of the rate ventilation air
will be delivered during the RECOVERY period indicating the time the
fan needs to operate relative to fan o time. Fan Recov Ratio is calcu-
lated as follows:
Fan Recov Ratio = (People Portion * (CO2 Last – CO2 Base) / (CO2
Max – CO2 Base) + 1-People Portion) * (OA Full / OA Recov Pos)
Where:
People Portion = (OA % Full – OA % Area) / (OA % Full)
and
Fan Recov Timer = 3 min + [(Fan O Timer + 5) * Fan Recov Ratio]
NOTE: OA % Full and OA % Area are internal AVs and are not the
same as OA Full and OA Area, which are adjustable from the
U/I.
During RECOVERY mode, the damper is set to OA Recov Pos while the
supply fan operates for Fan Recov Timer minutes. The Ventilation Mode
is set to RECOVERY during this period.
At the conclusion of the Fan Recov Timer period:
1. If there is a call for heating, cooling, or economizer that requires fan
operation, Ventilation mode is set to NORMAL and ventilation pro-
ceeds accordingly.
2. If the Occupied Fan mode is set to AUTO and there is no call for heat-
ing, cooling, or economizer, the supply fan stops unless Space CO2
exceeds CO2 Max – 100 ppm, in which case the fan operates with the
OA damper at OC Recov Pos as determined above until Space CO2
<= CO2 Max.
Economizer Ventilation
When economizer cooling is called for, the OA damper shall maintain
the economizer setpoint or the ventilation setpoint, whichever is greater.
Ventilation Override Mode
When activated through the U/I or by seing Vent Ovrd Mode to ON at
priority 8 via software, a ventilation override mode shall activate the fan
for Vent Ovride minutes (30 default) with the OA damper at OA Full.
Standby Mode (Requires a Motion Sensor)
If Standby operation is enabled and Standby Mode is ACTIVE, the fol-
lowing shall occur:
1. Active heating and cooling setpoints are adjusted as in normal
STANDBY mode.
2. If the fan is operating, fan operation based on Fan Max O shall be
suspended and Fan O Timer shall be reset to zero. If the fan is o
when the STANDBY mode initiates, Fan O Timer shall be suspend-
ed at its current value until occupancy is again detected.